#include "rtweekend.h"

#include "camera.h"
#include "color.h"
#include "hittable_list.h"
#include "material.h"
#include "sphere.h"

#include <iostream>

// 这是一个递归函数，代表光线反射的次数
color ray_color(const ray &r, const hittable& world, int depth) {
	hit_record rec;
	// 不需要更多的反射光线了，停止吧
	if (depth <= 0) {
		return color(0, 0, 0);
	}
	if (world.hit(r, 0.001, infinity, rec)) {
		ray scattered;
		color attenuation;
		if (rec.mat_ptr->scatter(r, rec, attenuation, scattered)) {
			return attenuation * ray_color(scattered, world, depth - 1);
		}
		return color(0, 0, 0);
	}
	vec3 unit_direction = unit_vector(r.direction());
	auto t = 0.5 * (unit_direction.y() + 1.0);
	return (1.0 - t) * color(1.0, 1.0, 1.0) + t * color(0.5, 0.7, 1.0);
}

hittable_list random_scene() {
	hittable_list world;

	auto ground_material = make_shared<lambertian>(color(0.5, 0.5, 0.5));
	world.add(make_shared<sphere>(point3(0, -1000, 0), 1000, ground_material));
	
	for (int a = -11; a < 11; a++) {
		for (int b = -11; b < 11; b++) {
			auto choose_mat = random_double();
			point3 center(a + 0.9 * random_double(), 0.2, b + 0.9 * random_double());

			if ((center - point3(4, 0.2, 0)).length() > 0.9) {
				shared_ptr<material> sphere_material;
				if (choose_mat < 0.8) { // diffuse
					auto albedo = color::random() * color::random();
					sphere_material = make_shared<lambertian>(albedo);
					world.add(make_shared<sphere>(center, 0.2, sphere_material));
				} else if (choose_mat < 0.95) { // metal
					auto albedo = color::random(0.5, 1);
					auto fuzz = random_double(0, 0.5);
					sphere_material = make_shared<metal>(albedo, fuzz);
					world.add(make_shared<sphere>(center, 0.2, sphere_material));
				} else { // glass
					sphere_material = make_shared<dielectric>(1.5);
					world.add(make_shared<sphere>(center, 0.2, sphere_material));
				}
			}
		}
	}
	
	auto material1 = make_shared<dielectric>(1.5);
	world.add(make_shared<sphere>(point3(0, 1, 0), 1.0, material1));

	auto material2 = make_shared<lambertian>(color(0.4, 0.2, 0.1));
	world.add(make_shared<sphere>(point3(-4, 1, 0), 1.0, material2));

	auto material3 = make_shared<metal>(color(0.7, 0.6, 0.5), 0.0);
	world.add(make_shared<sphere>(point3(4, 1, 0), 1.0, material3));
	return world;
}

int main(){
	const auto aspect_ratio = 16.0 / 9.0;
	const int image_width = 1200;
	const int image_height = static_cast<int>(image_width / aspect_ratio); // 675
	const int samples_per_pixel = 10;
	const int max_depth = 50;

	std::cout << "P3\n" << image_width << ' ' << image_height << "\n255\n";

	auto world = random_scene();

	point3 lookfrom(13, 2, 3);
	point3 lookat(0, 0, 0);
	vec3 vup(0, 1, 0);
	auto dist_to_focus = (lookfrom - lookat).length();
	auto aperture = 0.1;

	camera cam(lookfrom, lookat, vup, 20, aspect_ratio, aperture, dist_to_focus);

	for (int j = image_height - 1; j >= 0; --j) {
		for (int i = 0; i < image_width; ++i) {
			color pixel_color;
			for (int s = 0; s < samples_per_pixel; ++s) {
				auto u = (i + random_double()) / (image_width - 1);
				auto v = (j + random_double()) / (image_height - 1);
				ray r = cam.get_ray(u, v);
				pixel_color += ray_color(r, world, max_depth);
			}
			write_color(std::cout, pixel_color, samples_per_pixel);
		}
	}
	return 0;
}
